The phrase "on the inside" can be essentially synonymous with "internally" or "inwardly," meaning something that occurs or exists within the inner workings of a person or object. However, there are a variety of other phrases one could use in place of "on the inside" to convey a similar or related idea. These could include "deep down," "beneath the surface," "inwardly focused," "innermost," "core-located," "rooted," or "at the heart of." Regardless of the specific phrasing used, the common thread throughout is an emphasis on something that occurs or exists within the depths or core of a person or object.